Outbreak of suspected pertussis in Kaltungo, Gombe State, Northern Nigeria, 2015: the role of sub-optimum routine immunization coverage

Abstract

Introduction Despite the availability of vaccines, pertussis outbreaks still occur in developing countries. In December 2015 we investigated a pertussis outbreak in Kaltungo, Nigeria to identify determinants of infection and institute control measures. Methods We enrolled 155 cases and 310 unmatched controls. We defined cases as residents of Kaltungo with paroxysmal or whooping cough lasting 2 weeks with or without vomiting and randomly selected neighborhood controls. Using structured questionnaire, we collected data on socio-demographics, clinical and risk factors. We collected twelve nasopharyngeal swabs for laboratory analysis using Polymerase Chain Reaction. Results Median age was 24 months (range 1-132 months) for cases and 27 months (range 1-189 months) for controls. Female cases and controls were 86 (55.5%) and 150 (48.4%) respectively. A total of 83 (56.6%) cases were in age group 12-59 months. Age-specific-attack-rate was 83/1,786 (4.7%); Age-specific-case-fatality-rate was 21/83 (25.3%); Age-specific-proportional-mortality-ratio was 21/24 (87.5%). A total of 61 (39.4%) zero doses and 30.1% Pentavalent dropouts were documented. Multivariate analysis revealed parental refusal (adjusted OR = 27.8; CI = 8.8-87.7), contact with a case (AOR = 7.9, CI = 4.3-14.7, P = 0.000), belonging to the Muslim faith (AOR = 2.0; CI = 1.1-3.5) and having mothers with informal education only (AOR = 4.7, CI-2.6-8.4) as independent predictors of pertussis infection. Conclusion Sub-optimal vaccination due to parental refusal and informal education of mothers were major determinants of pertussis infection. We conducted awareness campaigns of key immunization messages targeted at the informal education sector. We ensured appropriate case management, contact vaccination and health education in public gatherings, worship places and schools.

An epidemiological investigation of the 2019 suspected pertussis outbreak in northwestern Nigeria

“…Regarding the overall case fatality rate, our study found a much lower case fatality rate than the previous studies conducted in Gombe State, Northeastern Nigeria, and Ethiopia. 12,13,15 However, our study finding is comparable to a study published in 2009 from Argentina where case fatality rate was 0.17% based on analyzed outbreaks data. 19 Furthermore, we found a sex difference in case fatality rate, suggesting that males are more likely to die of pertussis when infected than females.…”

“…Our result is not different from previous studies that reported the protective effect of full vaccination against pertussis. 13,15…”

Bordetella pertussis in School-Age Children, Adolescents, and Adults: A Systematic Review of Epidemiology, Burden, and Mortality in Africa

“…There were five studies which reported epidemiology data for pertussis in Africa, namely Senegal [ 27 ], Tunisia [ 28 ], Algeria [ 29 ], Nigeria [ 30 ], and Uganda [ 31 ], and seven studies which reported sero-epidemiology in Senegal [ 32 ], Cameroon [ 33 ], South Africa [ 34 ], Tunisia [ 35 , 36 ], Morocco [ 37 , 38 ], and Gambia [ 39 ]. There were seven studies with mortality data including Nigeria [ 30 , 40 ], Ethiopia [ 41 ], Morocco [ 42 ], South Africa [ 43 , 44 ], and Senegal [ 27 ].…”

“…In Nigeria, based on a clinical definition, and a population of 155 young children and adolescents of undefined age (5 cases in children aged 10–14 years) [ 30 ], the overall pertussis attack rate of suspected cases was 155/11,172 (1.4%), and the CFR was 24/155 (15.5%). The authors noted that the CFR was highest in those aged 12–59 months.…”

“…There was one study identified in Nigeria which discussed an outbreak in Kaltungo in 2015, with an overall attack rate of clinically diagnosed pertussis cases of 155/11,172 (1.4%), of which 56.6% of were among children aged 1–5 years. Suboptimal vaccination was a major factor in the outbreak, with 39.4% of children having received zero doses of pertussis vaccine, which was due partly to parental refusal to vaccinate, religion, and low educational status of mothers [ 30 ].…”